The optima choke tube is longer and slimmer than conventional mobilchoke tubes.Thanks to the elongated cone it minimize pellet deformation and improve shot patterns.The various versions are fully interchangeable on 12 gauge guns with optima bore barrels.The choke tube is for 12 gauge shotguns with the optima-choke system only.Approved: Steel,Lead,Non-ToxType: ExtendedGauge: 12 GaugeConstriction Type: CylinderConfiguration: OptimaFinish: Silver w/Colored BandConstrictiondiameter: .732Chokes Included: 1Recommended For: 20 ydsMaterial: 17-4 Stainless SteelPorted: No